1. Technical Field
The present invention relates to a ventilation apparatus for removing moisture from an interior of a fuel cell stack enclosure, and a control method thereof.
2. Description of the Related Art
A fuel cell system is a generation system that directly converts chemical energy of fuel into electrical energy. A fuel cell system includes a fuel cell stack generating electrical energy, a fuel supply device supplying fuel to the fuel cell stack, an air supply device supplying oxygen in the air as an oxidizing agent required for an electrochemical reaction to take place in the fuel cell stack, and a heat and water managing device removing a heat of reaction of the fuel cell stack to outside of the system and controlling an operation temperature of the fuel cell stack.
With this configuration, the fuel cell system generates electricity by the electrochemical reaction between hydrogen as fuel and oxygen in the air, and discharges heat and water as reaction products.
A fuel cell stack applied to a fuel cell vehicle is formed by continuously arranging unit cells, and in each unit cell, a membrane-electrode assembly (MEA) is positioned in the innermost portion. The MEA includes an electrolytic membrane capable of moving hydrogen ions, and catalytic layers, namely, a cathode and an anode, coated on both surfaces of the electrolytic membrane to allow hydrogen and oxygen to react with each other. Also, gas diffusion layers (GDLs) are positioned outside of the MEA, namely, outside of the cathode and the anode. Separators are positioned outside of the GDLs to supply fuel and air to the cathode and the anode and having a flow path formed to discharge water generated due to a reaction. End plates are positioned at both ends of the stack to hold the structure of the stacked cells.
In the stack, hydrogen and oxygen are ionized according to a chemical reaction by their respective catalytic layers, whereby an oxidization reaction occurs in an electrode to which hydrogen is supplied to generate hydrogen ions and electrons, and a reduction reaction occurs in an electrode to which oxygen is supplied to generate water as oxygen ions and hydrogen ions are reacted.
In general, a catalyst formed by including a platinum catalyst and a cocatalyst in a catalyst support formed of carbon is mainly used as an electrode catalyst used in a fuel cell. Namely, hydrogen is supplied to an anode, and oxygen is supplied to a cathode. Thus, hydrogen supplied to the anode is decomposed into hydrogen ions and electrons by the catalyst of the electrode layers formed on both sides of an electrolytic membrane. Among them, only the hydrogen ions selectively pass through the electrolytic membrane as a cation exchange membrane and are transmitted to the cathode. At the same time, electrons are transmitted to the cathode through a gas diffusion layer and a separator as conductors. In the cathode, the hydrogen ions supplied through the electrolytic membrane and the electrons transmitted through the separator meet oxygen in the air supplied to the cathode by the air supply device to cause a reaction of generating water. Due to migration of the hydrogen ions at this time, electrons flow through an external conducting wire, generating a current, and heat is incidentally generated in addition to water.
In general, in order to physically protect a fuel cell stack in which a high voltage is formed, the stack is housed in an enclosure. However, due to moisture introduced through a gap of the enclosure, moisture condensed due to a difference in temperature between an interior and an exterior of the enclosure due to exothermic reaction of the stack, or moisture partially leaked from the stack when the stack is operated, or the like, stack components within the enclosure is corroded or insulation resistance is degraded.
To overcome problems with conventional fuel cell stacks, the present invention proposes an apparatus for determining a moisture-removed environment within a stack enclosure and ventilating an interior of the enclosure, and a control method thereof.
The matters described above as a background art are merely described to promote understanding of the background of the present invention and should not be admitted as corresponding to a related art already known to a person skilled in the art.